In recent years, research has been conducted on techniques of automatically controlling one or both of the acceleration-and-deceleration and steering of a subject vehicle. On the other hand, there is known a towed-object connection detector (for example, see Japanese Unexamined Patent Application Publication No. 2010-152732) including a towed-object connecting unit, a traveling-state detecting unit, an object detecting unit, and a determining unit. The towed-object connecting unit is provided so that an object to be towed can be connected behind the vehicle. The traveling-state detecting unit detects a traveling state on the basis of the velocity of the vehicle. The object detecting unit is provided on the back of the vehicle and detects the presence of an object within a predetermined distance from the external surface of the vehicle. The determining unit determines that the object to be towed is connected to the towed-object connecting unit if the object detecting unit detects the presence of the object for a predetermined period or longer in the state where the traveling-state detecting unit detects forward movement of the vehicle at a predetermined velocity or higher.
However, in the related art, there is no technique to implement automatic driving in accordance with a towing state.